Objective　To explore the possible mechanism in childhood Dent disease combined with renal cystic disease. Methods　Clinical data were collected and analyzed from 1 childhood Dent disease cases combined with renal cystic disease. Results　The case presented with nephrotic level low-molecular weight proteinuria, hypercalciuria, progressive renal failure, multiple cysts in both kidney and hypopotassemia. Renal biopsy showed focal segmental glomerulosclerosis combined with tubulointerstitial damage. Gene mutation analysis showed a hemizygous mutation (c.1975delC, p.R659Gfs*7) in CLCN5 gene, and no positive result on nephronophthisis related genes was found. Conclusions　Dent disease combined with renal cystic disease is a rare phenomenon, with reasons unknown.